Lunar Tidal Deformation and the Internal Structure of the Moon

Abstract

Monitoring tidally-induced deformations of the Moon from orbiting and landed spacecraft would provide important clues on the constitution of the lunar interior, thereby augmenting the Apollo seismic data record. A major advantage is that the tidal forcing function for a synchronously rotating satellite like the Moon is accurately known and precise tidal potential catalogues can be produced. A higher temporal resolution and precision than with space techniques alone can be achieved by additionally emplacing one or several landers on the lunar surface. However, tidal measurements may be significantly impeded by instrumental drift, instrument coupling to the surface, and local sources of noise. We will present relations between key tidal parameters that can be retrieved from an instrument suite monitoring tidally-induced changes of local gravity, tilt, latitude and strain at the surface and the constitution of the deep interior of the Moon. A most promising approach would involve time-varying gravitational field observations from an orbiting spacecraft combined with long-term monitoring of tidally-induced gravity changes at the lunar surface.